Porcelain veneers correct color, shape, and alignment but do not really fix over-bite or over-jet. (only minimal) You would need invisalign or braces to correct this.
Over-jet is the horizontal space between the upper and lower teeth when you are in full normal bite. In other words, when you bite together, the space you feel with your finger between the upper and lower front teeth. So this is a horizontal overlap of upper and lower front teeth.
Over-bite is how much the upper teeth overlap over the lower teeth in full normal bite. So this is a vertical overlap of upper and lower front teeth.
With this in mind, veneers generally make teeth slightly longer and/or thicker depending on what the person needs, so this would make over-bite and over-jet slightly larger (increase in both) but not significantly.
Hope this helps.
Dr. T